1. Field of the Invention
The present invention relates to an organic electro-luminescent device provided with an electric light emitting elements used for displays, and display light sources, and the like, a manufacturing method for the same, and electronic equipment.
2. Background Art
Recently, the development of light emitting elements using organic materials for spontaneous light emitting-type displays in place of liquid crystal displays has been proceeding at a rapid pace. With respect to an organic electro-luminescent device equipped with a light emitting component using an organic material in the light emitting layer, a method for forming a low molecular weight layer using an evaporation process (disclosed from page 913 in Appl. Phys. Lett. 51 (12), 21 Sep. 1987), and a method for coating a large molecular weight layer (as disclosed from page 34 of Appl. Phys. Lett. 71 (1), July 1997) are principally known.
In the case of using a low molecular weight material as a means for coloring, a light emitting material differing from that of mask lifting is vapor deposited and formed onto the desired image. On the other hand, in the case of a large molecular weight material, much attention is being placed on performing the coloring using an ink jet method, due to refinement and ease with which the patterning can be accomplished. The following conventional examples are known as methods for forming an organic electro-luminescent component by means of such an ink jet method: Japanese Patent Application, First Publication No. Hei 7-235378, Japanese Patent Application, First Publication No. Hei 10-12377, Japanese Patent Application, First Publication No. Hei 10-153967, Japanese Patent Application, First Publication No. Hei 11-40358, Japanese Patent Application, First Publication No. Hei 11-54270, and Japanese Patent Application, First Publication No. Hei 11-339957.
In addition, from the standpoint of component manufacturing, in order to improve the light emitting efficiency and durability, the formation of an hole injection/transport layer between the electrode and light emitting layer is widely performed (disclosed from page 913 in Appl. Phys. Lett. 51 (12), 21 Sep. 1987). Hitherto, formation of a layer has been performed by means of a coating process such as spin coating or the like, using a conductive macromolecule as the buffer layer and/or hole injection/transport layer, e.g., a polythiophene derivative and/or polyaniline derivative (Nature, 357, 477, 1992). With respect to a low molecular weight material, formation of a layer using a phenylamine derivative, as the hole injection/transport layer, by means of evaporation has been reported.
The aforementioned ink jet methods are extremely effective as a means for simply forming a layer having a refined pattern without wasting the light emitting layer material comprising the organic electro-luminescent material.
When forming a light emitting layer using an organic electro-luminescent material according to an ink jet method, a composition is employed which comprises a solute and solvent, wherein the aforementioned solute comprises an organic electro-luminescent material.
As the aforementioned composition, it is possible to use a composition comprising only one type of organic electro-luminescent material, however, compositions comprising a plurality of organic electro-luminescent materials are more widely used. For example, by means of mixing a light emitting material and a fluorescent material, it is possible to change the light illuminated from the aforementioned light emitting material to a light having a different wavelength due to the presence of the aforementioned fluorescent material.
In this manner, in the case of a plurality of organic electro-luminescent materials, in order to obtain the desired light characteristics, it is necessary to form a layer in a state in which each of the aforementioned organic electro-luminescent materials is uniformly mixed without separation therefrom.
However, the droplets used in the formation of a thin layer according to the ink jet method are extremely small, and the evaporation time is short. As a result, the solvent molecules that are evaporated from the droplets are saturated prior to being sufficiently dispersed from the substrate area, such that even the resultant thin layer is re-dissolved. Furthermore, at the time of re-dissolving the aforementioned, the respective organic electro-luminescent materials phase separate from each other, which in turn results in problems, such as degradation of the performance characteristics of the organic electro-luminescent device.